The full story...

Early weight gain in babies linked to IQ

PETER LLOYD: New research has linked greater weight gain in the first month of baby's life to a higher IQ at early school age.

The study found babies who put on 40 per cent of their birth weight in the first four weeks had an IQ 1.5 points higher by the time they were six years of age, compared with babies who only put on 15 per cent of their birth weight. The research is from the University of Adelaide and has is published in the International Journal of Paediatrics.

But one nutrition expert warns there needs to be more work done to fully establish just how much a baby needs to grow in its earliest months.

Miriam Hall reports.

MIRIAM HALL: Every day since her son was born Dominique Hutchinson has learnt something new.

DOMINIQUE HUTCHINSON: Yeah it's been a bit of a learning curve. Today, he had is first couple of responsive smiles to me, so that was very exciting; so had the camera out for that. Getting to know him and how he's changing is really exciting actually.

MIRIAM HALL: Her baby Darcy is a month old and she closely monitors his development, particularly his weight.

DOMINIQUE HUTCHINSON: Being able to see him grow means that I feel comfortable in knowing that I've been supplying enough milk for him. Each time we've gone to the midwife we've had him weighed, and he's had significant jumps in his weight each week.

MIRIAM HALL: A baby's weight gain has long been known to be important for its physical and mental development. Now scientists say they have an indication that weight gain in the first four weeks may be crucial.

A team of Australian and Canadian researchers analysed data collected from 14,000 healthy babies in Belarus. They found babies who put on 40 per cent of their birth weight in the first four weeks had an IQ 1.5 points higher by the time they were six years of age, compared with babies who only put on 15 per cent of their birth weight.

Dr Lisa Smithers is a postdoctoral fellow at the University of Adelaide. She led the study, and wasn't surprised by the result.

LISA SMITHERS: It pointed, other pieces of the literature pointed to this kind of effect. But nobody's really also looked at that really early period, those first four weeks of life. So this was additional to that other research that says growth in the first year; well actually what we've shown is growth in those first four weeks is also very, very important.

MIRIAM HALL: She says it's significant because it looks at the weight gain of healthy babies, and focuses on the first month of their life. She stresses that babies should never be force fed, but she does think parents need to pay careful attention to weight gain when a baby is under a month old.

LISA SMITHERS: We do just want to point out the fact that parents should seek help for any feeding problems or any growth problems very early so that they can be addressed.

MIRIAM HALL: Dr Lisa Smithers points out that while weight gain is important in the first four weeks, rapid growth weight in a child's early years is often considered to be unhealthy.

LISA SMITHERS: A lot of people believe that rapid growth in infancy is bad for the baby's potential future health; so in terms of their obesity, their blood pressure. So what we want to do is bring some balance to that debate and say, well, even if early rapid weight gain is bad for babies' cardiovascular health, it seems to be important for babies' IQ scores.

MIRIAM HALL: Dr Beverly Muhlhausler is a medical research scientist at the University of Adelaide who specialises in the role of early nutritional environments. She agrees that there is scientific literature that indicates higher weight gain in early life is not necessarily a good thing.

BEVERLY MUHLHAUSLER: There's been a lot of talk about that, that early period, and should we, you know, what's the optimal sort of trajectory of weight gain. But there has been a view that really rapid weight gain early on is predictive of later problems in relation to high risk of obesity and risk of diabetes and so forth.

MIRIAM HALL: She says this is the first study she's seen that links weight gain in the first four weeks of a baby's life to IQ, and says it's a significant and interesting finding. She wants further investigation in the area.

BEVERLY MUHLHAUSLER: We still don't have a full understanding of the possible, you know, weighing up the negatives and positives of particular interventions and particular types of nutrition. So it may be growing a bit faster is associated with IQ - higher IQ later on, but may also be associated with an increased risk of metabolic disease.

So it's probably still too early days to go out and recommend, make any recommendations in terms of changing the growth profile that we are currently recommending.

MIRIAM HALL: For mother Dominique Hutchinson, she's just focused on each day with her young baby.

DOMINIQUE HUTCHINSON: At our first midwife appointment, we talked to her about percentages and where he should be up to. And she just said, basically as long as he's progressing and he looks happy and he's acting like a normal baby and doing all the normal milestones, just watching him and being content with how he's going.